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The activation of Rac1 by M3 muscarinic acetylcholine receptors involves the translocation of Rac1 and IQGAP1 to cell junctions and changes in the composition of protein complexes containing Rac1, IQGAP1, and actin. J Biol Chem 2002 Sep 06;277(36):33081-91

Date

06/19/2002

Pubmed ID

12070151

DOI

10.1074/jbc.M202664200

Scopus ID

2-s2.0-0037031481 (requires institutional sign-in at Scopus site)   21 Citations

Abstract

The abilities of the M(3) muscarinic acetylcholine receptor (mAChR) and Rac1 to regulate similar cellular responses, including cadherin-mediated adhesion, prompted us to investigate Rac1 regulation by M(3) mAChR. We characterized changes in Rac1 induced by stimulating transfected M(3) mAChR in Chinese hamster ovary cells stably expressing hemagglutinin (HA)-tagged wild-type or mutant Rac1. mAChR activation converts endogenous Rac1 to the GTP-bound form in cells expressing HA-Rac1 but not in cells expressing dominant negative HA-Rac1(Asn-17) or constitutively active HA-Rac1(Val-12). The competitive binding of endogenous IQGAP1 by HA-Rac1(Val-12) may diminish the mAChR-mediated activation of endogenous Rac1. HA-Rac1 and HA-Rac1(Val-12), but not HA-Rac1(Asn-17), accumulate with IQGAP1 at cell junctions during mAChR-induced cell-cell compaction. Co-localization studies suggest that Rac1 can accumulate at junctions without IQGAP1, but IQGAP1 cannot accumulate at junctions without Rac1. mAChR activation also induces GTP-independent changes in Rac1 because mAChR activation redistributes HA-Rac1(Asn-17), which does not bind GTP. Actin associates with complexes containing HA-Rac1 or HA-Rac1(Val-12) after prolonged mAChR activation. We also demonstrate that Rac1 participates in mAChR-induced cell-cell compaction and c-Jun phosphorylation. These results indicate that M(3) mAChR activation converts Rac1 to the GTP-bound form, alters interactions between Rac1, IQGAP1, and actin, and causes the junctional accumulation of Rac1 and IQGAP1.

Author List

Ruiz-Velasco R, Lanning CC, Williams CL

Author

Carol L. Williams PhD Professor in the Pharmacology and Toxicology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Actins
Animals
Blotting, Western
CHO Cells
Carrier Proteins
Cell Line
Cell Membrane
Cricetinae
Genes, Dominant
Glutathione Transferase
Microscopy, Fluorescence
Mitogen-Activated Protein Kinase 1
Mitogen-Activated Protein Kinase 3
Mitogen-Activated Protein Kinases
Models, Biological
Mutation
Phosphorylation
Plasmids
Precipitin Tests
Protein Binding
Protein Structure, Tertiary
Protein Transport
Receptor, Muscarinic M3
Receptors, Muscarinic
Signal Transduction
Time Factors
Transfection
p21-Activated Kinases
rac1 GTP-Binding Protein
ras GTPase-Activating Proteins